JP5583360B2 - Purification equipment for contaminated soil - Google Patents

Description

  The present invention relates to detoxification technology for decomposing and detoxifying heavy metals, organochlorine compounds, volatile organic compounds, etc. contained in contaminated soil, and in particular, clean soil that can be used for decontamination by detoxifying contaminated soil such as factory sites. It is related to the technology. According to the present invention, heavy metals can be insolubilized by reduction treatment of contaminated soil for soils exceeding the soil content reference value of heavy metals.

  Examples of waste that contains organic substances and / or heavy metals include soils such as old factory sites where various chemicals such as chemical factories have been handled for many years, or so-called shredder dust, which combine various harmful substances. In many cases, there are no suitable treatment methods, such as a major change in the components depending on the location where the waste is generated. The biggest problem with landfill disposal is that pollutants flow into groundwater and cause environmental pollution. Therefore, in recent years, wastes containing harmful organic substances and heavy metals are becoming difficult to landfill. Another problem is that the landfill itself is becoming scarce.

As a processing technique for the above-mentioned waste other than landfilling, a method of dry distillation of organic matter is performed in organic contaminated soil or the like, but this makes it difficult to remove heavy metals. In recent years, a rational waste disposal method has also been proposed in which inorganic waste is supplied to a cement kiln together with cement raw material or fuel and used as part of the raw material. Regarding the treatment of hazardous waste containing heavy metals and soil contaminated with heavy metals, melting methods, methods using chemicals such as chelates, redox methods and Portland cement-based cements (3CaO · SiO ₂ ; C ₃ S, 2CaO · Solidification stabilization by SiO ₂ ; C ₂ S system) is performed. In particular, the stabilization of solidification with Portland cement-based cement is because the cement is inexpensive, and due to its hydraulic properties, the treated object can be made into a hardened body, or the object containing much water or granular Since the object can be easily handled, it is implemented as a general-purpose method because of superiority in work such as transportation. This Portland cement cement has the property of generating calcium silicate and Ca (OH) ₂ when in contact with water, and the generated Ca (OH) ₂ has a high alkalinity of pH 12 or higher in a saturated state. Show.

However, this high alkalinity becomes a problem depending on the heavy metal species, and may tend to increase the amount of elution. In particular, amphoteric metals, such as lead and zinc, are safe for solidifying and stabilizing with highly alkaline Portland cement because of their high solubility in the alkaline and acidic regions. I have doubts.
In addition to methods other than those described above, problems such as the cost and processing capacity of the melting method, the stability of the chelate method and the oxidation-reduction method, the cost of the chemicals used, and the amount of water used after treatment The reality is that it contains many workability problems such as transportation and storage.

In view of this, a heavy metal elution suppressing material is developed that has a low alkaline cement composition having a pH of 11 or less as a main component and suppresses elution of heavy metals and also suppresses elution of amphoteric metals such as lead and zinc. (See Patent Document 1).
However, it has not been possible to deal with waste that contains both combustible and non-combustible materials. For example, soil contaminated with highly volatile substances such as organic matter may be released into the atmosphere along with the kiln exhaust gas from the flue before being decomposed by heating if it is supplied together with cement raw materials, which may cause environmental pollution problems. Another problem is that soil contaminated with organic matter often contains a lot of halogens, alkali components, heavy metals, etc., and thus causes problems in production and quality when used as part of cement raw materials. That is, halogens such as chlorine, alkali components and heavy metal components that are brought into the firing process (kiln) react with each other at high temperature to form a metal halide that easily volatilizes, and usually starts to volatilize at a temperature of 900 ° C. or lower. The combustion gas flows in the kiln at a considerable flow rate, and the volatiles are mixed with the kiln exhaust gas and discharged. However, when the heat is exchanged with the raw material newly supplied by the preheater, the temperature falls below the dew point. Decreases, and returns to the kiln again due to adsorption to the raw material. Therefore, these metal halides circulate between the kiln and the preheater and are concentrated. This metal halide or the like exhibits adhesiveness in the preheater, and is fused to the inner wall to grow the raw material powder to agglomerate, which may cause blockage of the duct or the like of the preheater, which may hinder stable operation.

Further, when zinc content, cadmium content or other heavy metal content increases in the cement, there is a problem that the quality of the cement is deteriorated. It has been desired to develop a safe and inexpensive treatment method for waste containing organic substances and heavy metals that can solve such problems.
Therefore, the preheating step (a) and heating in a low oxygen state within a temperature range of 200 to 600 ° C., the solid content obtained by separating and removing the volatile components generated in the step (a) is used as a preheater for a cement kiln with a preheater together with a cement raw material. A step (b) of supplying, a step (c) of extracting heavy metal compound vapor together with the kiln exhaust gas from the extraction holes provided in the vicinity of the raw material supply part of the cement kiln, a step of recovering the extracted heavy metal compound by cooling and condensing (d) ) Has been proposed (see Patent Document 2).

  As a detoxification treatment method without a heating process, for example, a wide-area fluid path layer including many gaps communicating with each other is installed along the periphery of the boundary between the underground saturated zone and the unsaturated zone, A well-like structure that can communicate with the fluid path layer is installed. From this well-like structure, through the wide-area fluid path layer, fluid is injected into the periphery of the wide-area fluid path layer, and fluid control is performed by collecting the fluid from the periphery of the wide-area fluid path layer, which is used for soil pollution repair. Soil contamination countermeasures (see Patent Document 3) and cleaning efficiency capable of reducing the cost by further simplifying the recovery and injection of various fluids and implementing the fluid injection and recovery in a wider area. In order to provide a method for remediating contaminated soil that can reduce the cost of remediation of contaminated soil, it is easy to separate the contaminants from the soil and sand that are contaminated with contaminants such as oil and heavy metals. Sediment B with a particle size larger than the specified particle size is classified by a sorter, and the classified sediment is added to each classified soil A and B and introduced into the washing machine. The contaminants attached to the surface of the earth and sand by friction or the like are separated, and the water containing the earth and sand and the contaminants is introduced into a separation apparatus equipped with a water-filled separation tank, a vibration screen, and an air supply means. In this separation tank, a technique for separating earth and sand from contaminants by applying vibrations to the earth and sand and blowing bubbles to settle has been proposed (see Patent Document 4).

However, the conventional cleaning methods for soil as described above are not easy and inexpensive to implement at the site, and simply containing heavy metal contaminated soil has not been a fundamental solution.
From the above, it is said that there is an urgent need to develop effective means that can easily and inexpensively clean soil contaminated with oil and heavy metals locally.

JP 10-258263 A JP 2000-288527 A JP 2004-283709 A JP 2002-254063 A

The problem of soil contamination is very complex in terms of the type of pollutant and its nature. Environmental standards indicate heavy metals by element names, but each element has various forms, and the properties of each element vary greatly, requiring treatment according to the element. In the case of organic compounds, some of them are decomposed little by little in the soil, and harmful intermediate substances may be formed during the decomposition process. Furthermore, the underground structure and the geological structure are complex and there are many strata. Therefore, when implementing pollution control work, the responsibility for quality management, process management, and health and safety management in terms of operation is clearly clarified, and process management that does not adversely affect the surrounding environment such as inspection, measurement, and testing is always at a glance. It is necessary to understand.
Based on these matters, the present invention regenerates clean soil from soil contaminated with heavy metals, volatile organic compounds, etc., efficiently recovers soil that can be restored, and enables cost savings. An object of the present invention is to provide a soil regeneration processing apparatus. Another object of the present invention is to detoxify soil containing various pollutants by a simple operation of reducing the contaminated soil.

Heavy metals and volatile organic compounds contained in soil contamination must be responsibly detoxified in the area where they occur, and it is extremely difficult to leave the contaminated soil treatment to other regions. However, there is no method other than detoxification. It is an object of the present invention to provide a treatment technology for contaminated soil in accordance with the current situation, and to provide a new technology capable of detoxifying treatment on the site where the contaminated soil exists and effectively using the contaminated soil. And
Further, the contaminated soil detoxification apparatus of the present invention enables conversion of the contaminated soil into a substance (catalyst) useful for the treatment of the contaminated soil, achieves the detoxification treatment of the contaminated soil with the contaminated soil, The purpose is to reduce the use.
Moreover, this invention provides the detoxification apparatus of the contaminated soil using incineration ash, and aims also at the effective utilization of a waste material.

The present invention comprises the following technical means and comprises the following detoxification device for contaminated soil.
(1) Contaminated soil detoxification device, contaminated soil collection device, drying device for drying contaminated soil, magnetic sorting device for sorting dry contaminated soil into magnetic material-containing soil and non-magnetic soil, containing magnetic material Sorting device that removes metal or coarse particles with high specific gravity from soil, grinding device for sorted magnetic material-containing soil, reduction heat treatment device for magnetic material-containing soil, reduction of non-magnetic soil and reduced magnetic material-containing soil An apparatus for detoxifying contaminated soil, comprising: a charging apparatus for heat treatment apparatus; a reduction heat treatment apparatus for mixed soil; and a soil recovery apparatus for collecting the treated soil as soil that can be restored.
(2) The detoxification treatment apparatus for contaminated soil according to (1), wherein the heat treatment in the reduction heat treatment apparatus for the magnetic substance-containing soil is performed in a range of 400 to 600 ° C.
(3) The detoxification treatment apparatus for contaminated soil according to (1) or (2), wherein the heating temperature in the reduction heating apparatus for mixed soil is in the range of 300 to 600 ° C.
(4) The detoxification device for contaminated soil according to any one of (1) to (3), wherein the reducing atmosphere has an oxygen concentration of 6% or less.
(5) The detoxification device for contaminated soil according to any one of (1) to (4), wherein the magnetic material-containing soil is pulverized to 100 mesh or less by a pulverizer.
(6) The magnetic material-containing soil heat-treated in a reducing atmosphere with respect to 100 parts by weight of the non-magnetic soil, and 2 to 40 parts by weight are charged into the reduction heat treatment apparatus according to any one of (1) to (5) above Detoxification equipment for contaminated soil.
(7) The detoxification processing apparatus for contaminated soil according to any one of (1) to (6), further including an input device to the reduction heat treatment apparatus for the mixed soil of the incinerated ash or the incinerated ash reduction product.
(8) Described in any one of (1) to (7) above, which has a gas circulation path that detoxifies the exhaust gas from the reduction heat treatment apparatus of the mixed soil and circulates it to the drying apparatus via a sealed circuit Detoxification equipment for contaminated soil.

The conventional contaminated soil treatment technology is classified into a purification treatment method and a containment method, and the present invention corresponds to a purification treatment that is completely harmless by a reduction treatment with a catalyst at a low temperature.
(1) The present invention has low equipment cost (initial cost), no maintenance cost (running cost), simple equipment, does not require advanced technology, and emits carbon dioxide. It is characterized by few. Since high temperatures are not used, steel materials with low heat resistance can be used, and since there are less dangers compared to high temperatures, safety equipment is not complicated and can be simplified, so the system is simple, the plant manufacturing period is short, and the maintenance costs are power. This has the advantage of lower costs and fewer personnel.
(2) It is possible to make clean soil by decomposing, separating or detoxifying pollutants such as heavy metals, organochlorine compounds and volatile organic compounds contained in the soil.
(3) Since the recyclable resource plant for treating contaminated soil has a simple structure, it can be temporarily installed at the contaminated site.
(4) The recyclable resource plant of the present invention has been conducting verification tests on heavy metals and organochlorine compounds contained in incineration ash, etc. for the past 10 years since 1995, with the approval of the Director-General of the Environment Agency and the Minister of Health and Welfare. It is excellent in reliability because it is based on a new business approved by the Minister of International Trade and Industry as a new business.
(5) Since heavy metals contained in incinerated ash can be processed and reused as a detoxifying catalyst for contaminated soil, the treatment of incinerated ash has been demonstrated for three years in Shimokyu City, Tokyo, without any accidents. The result of the incinerated ash treatment technology that can be applied can be applied to the present invention.
(6) A part of the contaminated soil can be processed and used as a treatment agent (catalyst) for the contaminated soil.
(7) Of the heavy metals contained in the soil, the water-soluble metal compound can be replaced with a hardly soluble metal compound and can be usefully used as a catalyst for treating contaminated soil.
(8) Organochlorine compounds can be decomposed and converted into non-hazardous compounds in the heat treatment step.

It is drawing which shows the conventional incineration ash recycling plant system flow. It is drawing which shows the conventional detoxification processing equipment of incineration ash.

  Concerning the treatment of contaminated soil, for example, “Report of Expert Meeting on Soil Contamination Countermeasures in Toyosu New Market Plan, etc. 9. What measures should Tokyo take in the future” includes (1) Human health damage due to lifetime exposure. From the standpoint of preventing environmental pollution, the risk of human health damage from direct exposure to contaminated soil, exposure to contaminated groundwater, or exposure to contaminated air should be continuously prevented. It is said that. As a solution to prevent continuous exposure, the present invention detoxifies harmful metals in contaminated soil by making them the same substances as mineral resources existing in underground resources that do not dissolve in water, and also contains harmful substances other than metals. It is separated from the soil by decomposition or volatilization.

  The present invention includes (1) drying contaminated soil, (2) selecting magnetic material-containing soil and non-magnetic soil, (3) further pulverizing the classified magnetic material-containing soil, (4) in a reduction furnace Recombine molecules into stable metal compounds, (5) process magnetic material-containing soil into composite catalyst, (6) add and mix composite catalyst into non-magnetic soil, (7) mix non-magnetic soil in reduction furnace (8) It comprises a series of devices for carrying out each step, which is recovered as soil that can be recovered by catalyst treatment.

  An incineration ash treatment facility can be used for the detoxification device for contaminated soil of the present invention. For example, a processing apparatus for detoxifying and recycling incinerated ash disclosed in Japanese Patent Application Laid-Open No. 2001-942 and Japanese Patent Application Laid-Open No. 2000-24625 is used to heat-treat a processed material in a reducing atmosphere. When compared with the detoxification processing apparatus for contaminated soil of the present invention, the main processing apparatus is common in the heating apparatus. Therefore, the detoxification processing apparatus for contaminated soil according to the present invention can be constructed using the incineration ash processing apparatus as a skeleton. FIG. 1 shows a flow chart of a plant system of an incineration ash treatment apparatus using the reduction reaction described in the above-mentioned literature, and FIG. 2 shows an incineration ash reduction heating apparatus.

For example, a detoxification process for contaminated soil in which the present invention is carried out at a contaminated site will be described in detail. A temporary factory of about 10,000 m ² is installed in the contaminated site. The installation area of the plant is about 1,000 m ² per unit, and the same hypothetical factory may be installed at 10 locations. Contaminated soil is excavated and collected by a shovel car and transported to a recycling plant installed in the factory. The excavated contaminated soil is transported to a receiving hopper installed in front of the factory, and the plant is connected to a belt conveyor from the hopper. A dump truck is used from the excavation site to the hopper.

  After the treatment, the purified soil is subjected to inspection, and the soil that can be restored is passed back to the excavation site. It is preferable to spread the incinerated ash processed product described below obtained from the incinerated ash to a depth of 5 to 50 cm as much as possible in the deep layer of the site where the material is backfilled. When laying down, the strength can be adjusted and it will be a countermeasure against liquefaction. Treated incineration ash is cleared of all environmental standards, has strong catalytic performance, and has deodorizing, decolorizing, and sterilizing power, so it is also useful for soil contamination after incineration ash installation. This processed product of incineration ash is manufactured by a reduction detoxification process at a low temperature, and the inventor has a proven record of 10 years of incineration ash. Pollutants contained in incinerated ash (heavy metals, organic chlorine compounds, etc.) and pollutants contained in soil (heavy metals, volatile organic compounds, etc.) are both rendered detoxified by a catalyst through a reduction reaction in a reduced oxygen atmosphere. It is a possible substance.

As described above, the present invention excavates and removes contaminated soil, stops elution movement of harmful substances, disassembles and separates them, and purifies them, and can be used in temporary facilities for on-site processing. The contaminated soil is magnetically sorted by magnetic sorting into magnetic soil containing magnetic material and non-magnetic soil containing no magnetic material, but preferably using primary and secondary magnetic sorting devices, The total amount of the magnetic material-containing soil containing contaminated heavy metals is reduced, and only the contaminated soil contained in the non-magnetic soil is further sorted by a sorter to remove inappropriate impurities in the soil. The nonmagnetic soil is preferably pulverized to 100 mesh or less so that the reduction reaction proceeds over the entire soil.
The magnetic separator used in the present invention does not need to have a structure peculiar to soil treatment, and is appropriately selected from magnetic separators used in various industries.

  The selected non-magnetic soil is dried at a constant temperature and then mixed with magnetic material-containing soil and / or incinerated ash that has been heat-treated in a reduced oxygen atmosphere to form a residue through a reducing furnace in a reduced or reduced atmosphere. The existing heavy metals are recovered as insoluble metals and soil that can be restored. Volatile organic compounds contained in the contaminated soil are vaporized in a reduction furnace that maintains a temperature of around 400 ° C., and are collected or detoxified via a back filter. This detoxified nonmagnetic soil is used for embankment. In order to reduce the nonmagnetic soil, it is preferably performed in a reducing or oxygen-reducing atmosphere, and the oxygen concentration is preferably 6% or less. The reduction treatment is performed at 300 to 600 ° C., preferably 350 to 450 ° C.

After drying the magnetic material-containing soil in the same manner as above, high density metal is selected and removed by screening, and coarse particles are removed by sieving to make a fine powder with a pulverizer, and recombination of insoluble metal molecules in a reduction furnace. It is granulated so that it can be used as a catalyst, and it is used for the treatment of non-magnetic soil. Metals having a low specific gravity are converted into clean soil containing insoluble metals by reduction treatment and used as backfill soil. The reduction treatment of the magnetic substance-containing soil is preferably performed in a reducing atmosphere or a reduced oxygen atmosphere, and the oxygen concentration is preferably 6% or less. The reduction treatment is performed in the range of 350 to 600 ° C, preferably 350 to 450 ° C.
The blending ratio of the non-magnetic soil and the reduced magnetic substance-containing soil is determined according to the content of heavy metals in the contaminated soil, but usually the reducing treatment is performed on 100 parts by weight of the non-magnetic soil. By adding and mixing 2 to 40 parts by weight, preferably 5 to 20 parts by weight, of the magnetic substance-containing soil, the nonmagnetic section of the contaminated soil can be rendered harmless. Harmful organic compounds contained in the contaminated soil are decomposed or volatilized in the reduction treatment, and can be adequately dealt with by treating the exhaust gas discharged from the reduction treatment apparatus. This exhaust gas can be detoxified and used as a post-drying heat source.

  In the present invention, the incineration ash which is a mixture of different metals including heavy metals is efficiently mutually decomposed, and the same as the manufacturing process (equipment) for treating the incineration ash used for manufacturing heavy metal salts and metals as a composite catalyst. By using this technique, it is possible to detoxify contaminated soil and to produce clean soil below the environmental standard value. Clean soil refers to soil that contains only chemically stable substances. Except for artificially generated materials, these are metals that exist in the earth's crust as underground resource reserves, all of which can be resources, and humans dig and refine them into metal resources. What causes pollution is a metal compound that is primarily placed in an unstable state by a chemical reaction, and can be used as a resource by stabilization.

  The details of the present invention will be described in the following examples. The present invention is not limited to these examples.

  The contaminated soil detoxification device of the present invention is a drying furnace, a magnetic sorting device for magnetically separating magnetic material-containing soil and non-magnetic soil, a classification device, a pulverizing device, a first reduction reaction furnace, a second reduction reaction furnace, and a mixer. , Equipment such as smoke treatment equipment.

As the contaminated soil, soil collected from the factory site contaminated with benzene, cyanide, oil and heavy metals was used.
(1) Receiving / supplying equipment: receiving: raw ash receiving pit 100 m ³ , supplying: ash crane 13 ton / h, receiving hopper 10 m ³ , feeder 15 ton / h
(2) Dry the contaminated soil received in the contaminated soil drying facility until the moisture content is 10% or less.
(3) Sorting equipment: Grain size sorting: Vibrating sieve (screen mesh 20 mm, excluding grain size 20 mm or more, grain size 20 mm or less to the next process), sorting into magnetic substance-containing soil and non-magnetic soil by magnetic separator (4) Magnetic substance-containing soil Crushing treatment: crushing to a particle size of 100 mesh or less (5) Reduction reaction equipment: treating magnetic material-containing soil at a temperature of about 600 ° C., a treatment time of about 40 minutes, and an oxygen concentration of about 6%.
Main reaction: dechlorination of organic chlorine compounds; decomposition of dioxins in contaminated soil, thermal decomposition or scattering of organic chlorine compounds; progress of reduction reaction for heavy metal compounds, imparting catalytic activity.
(6) Crushing and crushing equipment: crushing equipment: removing particle size of 10-20 mm or less, crushing treatment: particle size 100 mesh (95%)
(7) Mixing 100 parts by weight of non-magnetic soil with 15 parts by weight of reduced magnetic substance-containing soil (8) Reduction reaction equipment: treatment temperature of about 300 ° C., treatment time of about 60 minutes, oxygen concentration of about 6% (Use of waste heat)
When the concentration of dioxins in the treated soil was measured, the “toxic equivalent” was “0.000”. Moreover, when the experiment for evaluating the elution of heavy metals in soil was carried out, no elution of heavy metals was observed.

  The contaminated soil was treated in the same manner as in Example 1. The amount of oxygen in the reduction reaction facility was set to 3% to suppress the oxidation reaction by the oxygen medium. In a reducing atmosphere, particularly harmful elements are more likely to react with sulfur than oxygen, and silicates are more likely to react with oxygen than sulfur.

(1) Drying process: Reduce moisture content of contaminated soil at a processing furnace temperature of 300 ° C (2% or less)
The exhaust gas from the reduction reaction equipment is used for drying.
(2) Furnace oxygen concentration 3% in the primary reaction treatment step (magnetic material-containing soil reduction treatment step), temperature 400 ° C .: Furnace oxygen concentration 3% in the secondary reaction treatment step (non-magnetic soil reduction treatment step), 300 ° C
(3) Mixing 5 parts by weight of magnetic substance-containing soil reduced with respect to 100 parts by weight of non-magnetic soil Effect: The same treated soil as in Example 1 was obtained.

  In Example 2, 5 parts by weight of magnetic substance-containing soil after reduction treatment and 5 parts by weight of incineration ash catalyst were added to 100 parts by weight of nonmagnetic soil to reduce the nonmagnetic soil. The soil after the treatment did not contain harmful compounds such as dioxins, volatile organic compounds, etc., and heavy metals contained in the soil were insolubilized, and the test results were superior to those of Example 2.

  In Example 1, instead of the reduced magnetic substance-containing soil, 15 parts by weight of the following incineration ash catalyst was mixed to reduce the non-magnetic soil, and the same detoxified soil as in Example 1 was obtained. It was.

  The production and characteristics of incinerated ash (also simply referred to as incinerated ash) that have been described so far and that have been activated in the catalytic ability and adsorption ability used in the examples and the like are described in detail below. This incinerated ash has catalytic activity, adsorption, and deodorizing properties. By adding and mixing 2 to 30 parts by weight with 100 parts by weight of the contaminated soil and performing a reduction treatment at 300 to 600 ° C., the contaminated soil can be rendered harmless. This detoxification treatment does not necessarily require reduction-treated magnetic substance-containing soil.

[Incinerated ash with activated catalytic ability and adsorption capacity]
Incineration ash used for detoxification of contaminated soil refers to incineration ash that has been subjected to intermediate treatment of municipal waste waste by incineration in a reduction furnace with a space of oxygen reduction atmosphere or reduction atmosphere. By contacting them, the incineration ash, which is a mixture of different metal compounds containing heavy metals, can be efficiently decomposed and reacted to convert heavy metals into sparingly soluble metal compounds and activate catalytic and adsorption capacities. A catalyst with activated catalytic capacity and adsorption capacity of incinerated ash, which is characterized by reprocessing, is produced.
Hereinafter, the production method and characteristics of the incinerated ash will be described in detail.

[Incineration ash]
A typical example of incineration ash used as a raw material is general incineration ash from municipal waste, but incineration ash containing various metal compounds can be used. Other examples of incineration ash include incineration ash of sludges such as activated sludge, sewage sludge and digested sludge, and incineration ash of industrial waste. Incineration ash that does not contain harmful dioxins is desirable. Some of these contain harmful substances such as cadmium, lead, and hexavalent chromium. Moreover, the types and contents of harmful substances are constantly changing. It can be said that it is a reliable method of treating incineration ash corresponding to these fluctuations.

[Crushing incineration ash into fine powder]
In order to use incineration ash as a catalyst, it is necessary to change the metal component of the incineration ash to a sparingly soluble metal compound, and in order to increase the catalytic performance, the incineration ash must be finely expanded to widen the surface of the metal component. Must be crushed. The surface area of the metal compound produced by pulverizing the incinerated ash is increased, the catalytic activity is increased, the reactivity with the titanium oxide to be added, and between the mixture of different metal compounds including heavy metals of the incinerated ash or Mutual decomposition and reaction with the oxide of titanium to be added becomes good. In the catalyst manufacturing method, a pulverization treatment step for expanding the surface area of the incinerated ash to be treated, preferably a pulverization treatment step for pulverizing fine particles of 100 to 300 mesh, more preferably 150 to 200 mesh, is provided before the reduction reaction treatment step. Is preferred.

[Titanium oxide]
Add titanium oxide to incineration ash as part of the raw material.
In general, the catalyst includes a metal catalyst and a metal oxide catalyst. Among the metal elements, transition metals such as iron, cobalt, nickel, copper, and white metals such as ruthenium, rhodium, palladium, osmium, iridium, and platinum dissociate hydrogen molecules to form hydrogen atoms and increase activation. Normally, the energy to dissociate hydrogen molecules is not dissociated without about 450 kilojoules of energy, but hydrogen atoms dissociate easily on the surface of nickel, rhodium, platinum, etc. at room temperature and adsorb on nickel, rhodium, platinum. To do. The driving force for this dissociation is the chemical affinity for hydrogen atoms on the metal surface. The dissociated hydrogen atoms are highly reactive and are added to hydrocarbons approaching the metal surface (such as ethylene and propylene) or added to organic compounds such as carbon and oxygen compounds to produce hydrogenated products. In addition, white metal, iron, cobalt, and nickel also dissociate hydrocarbon C—H bonds and perform hydrogenolysis. In this way, the catalyst has the ability to convert a metal molecule into an active metal atom and promote a chemical reaction without depending on a heat source.

  Incinerated ash contains unburned carbon C in addition to elements such as sodium, magnesium, aluminum, silicon, phosphorus, sulfur, chlorine, potassium, calcium, titanium, vanadium, chromium, manganese, iron, copper, zinc, and boron. It is a mixture of metallic and non-metallic compounds. Table 1 shows the seasonal variation in the types and contents of metals contained in incineration ash. Among the incinerated ash-containing metals, the contents of aluminum, silicon, chlorine, calcium, and iron are large.

Thus, incineration ash has many typical elements and few transition elements. Since transition metals such as titanium, vanadium, chromium, manganese, iron, copper, and zinc are too strong to bond with oxygen and become metal oxides, the reaction (combustion) system has reduced the oxygen content to 6% or less. A catalyst can be produced by heat treatment in a low oxygen state or a reduced state space. Transition metal oxides are divided into those that are active in oxidation reactions and those that are active in dehydrogenation reactions. For example, Fe ₂ O ₃ and Cr ₂ O ₃ are reduced to a metallic state even in the presence of hydrogen molecules. This is a good catalyst for dehydrogenation. Since Cr in the incinerated ash exists in the form of a compound that is easily soluble in water as CrO ₃ , it becomes Cr (OH) ₃ by reaction with hydrogen, and is stably insolubilized Cr ₂ O by the combustion process of Cr (OH) _{3. 3} On the other hand, typical metal oxides such as SiO ₂ , Al ₂ O ₃ , and MgO interact with a reaction molecule and acid-base, and activate the molecule by giving a proton to the reaction molecule or drawing a proton from the reaction molecule. . The catalyst of the present invention contains, as main components, iron oxide (Fe ₃ O ₄ ), titanium oxide (TiO ₂ or the like), potassium oxide (K ₂ O), alumina (Al ₂ O ₃ ), calcium oxide (CaO). , Silica (SiO ₂ ), magnesium oxide (MgO), and the like. Incineration ash has a larger activity as the outer surface area of the particles in the reactor increases, so the smaller the particle size, the better.

The raw material for producing incinerated ash with activated catalytic ability and adsorption capacity is mainly composed of incinerated ash and titanium oxide. Examples of titanium oxide include titanium oxide, titanate or Examples of the titanium composite oxide include calcium oxide, magnesium titanate, iron titanate, potassium titanate, sodium titanate, aluminum titanate, nickel, cobalt, zirconium, and a composite oxide containing titanium. Further, a pulverized material such as ilmenite, geiki stone, and vilophanite called titanium ore can be used without any special treatment.
As incineration ash, general incineration ash of municipal waste is a typical example as described above, but incineration ash containing various metal compounds can be used. Other examples of incineration ash include incineration ash of sludges such as activated sludge, sewage sludge, and digested sludge. Incineration ash 0.0001 to 0.01 wt%, preferably 0.0005 to 0.005 wt%, more preferably 0.001 to 0.005 wt% of titanium oxide as titanium By carrying out heat treatment, a reaction between the metal compounds contained in the combustion ash occurs, and the catalyst of the present invention (incinerated ash with activated catalytic ability and adsorption ability) is produced.

[Mixing incineration ash and titanium oxide]
Prior to refiring incineration ash such as general waste, sewage sludge, and industrial waste, oxides of titanium are added and adjusted so that the above ratio is obtained. When refiring, it is necessary to check the amount of titanium (titanium oxide) contained in the raw incineration ash, and the amount of titanium oxide added in consideration of the amount of titanium (titanium oxide) contained in the raw incineration ash Decide the amount. Therefore, incineration is performed by adding powdered titanium oxide during re-incineration. By doing so, incineration ash, which is a mixture of dissimilar metal compounds containing heavy metals, can be efficiently decomposed and reacted at a low temperature of around 300 ° C. by the catalytic action of titanium oxide, and heavy metals are hardly soluble metals. It can be reprocessed into a catalyst by changing to a compound and activating the catalytic ability and adsorption ability.

[Heating in a low oxygen or reducing atmosphere]
Incineration ash is usually a mixture of oxides of metals or non-metallic elements, and in some cases, toxic substances can be generated, so the oxidation reaction is minimized and the metal oxides are brought close to the metallic state and coexist at the same time. In order to promote the reaction between metals, it is preferable to heat in an inert gas atmosphere or a reducing atmosphere. In the presence of titanium oxide, in a low oxygen atmosphere or a reducing atmosphere, harmful substances contained in the incineration ash can be removed or detoxified in the step of producing the catalyst from the incineration ash. Usually, in order to decompose and remove dioxins from incineration ash, it is considered that the treatment temperature is preferably set to an ambient temperature of about 900 ° C. in consideration of complete decomposition of dioxins. When a heat treatment process is performed at a furnace temperature of 800 to 900 ° C. to reduce the moisture content of the incinerated ash in a short time (2% or less), dioxins in the exhaust gas may be pyrolyzed at the same time. Good. However, this drying step is not always necessary, and it is preferable to remove dioxins simultaneously with the subsequent reduction heating step.

An inert gas is used to adjust the reaction atmosphere. For example, nitrogen (N ₂ ) gas is circulated. When nitrogen (N ₂ ) gas is used as the inert gas, the molecular weight of nitrogen gas is 28, and its thermal characteristics (heat capacity, thermal conductivity, heat transfer coefficient, etc.) are almost different from air with a molecular weight of 29. There is no change in the drying characteristics of both. Since stable operation cannot be maintained unless the temperature and humidity of the gas sent from the heater to the drying device are always constant, a heat recovery unit that performs gas heat exchange so that the temperature condition is also constant for the return to the heater. It is suitable to attach.

  In order to produce incinerated ash with activated catalytic ability and adsorption ability (hereinafter also referred to simply as catalyst), the incinerated ash and titanium oxide are mixed and then heated in a low oxygen atmosphere or a reducing atmosphere. The purpose of this is to minimize the oxidation reaction by the atmosphere and to promote the reaction between the coexisting metals simultaneously with bringing the metal oxide close to the metal state. In the catalyst production method, it is preferable to provide a pulverization treatment step for expanding the surface area of the incinerated ash to be treated, preferably a pulverization treatment step for pulverizing the fine particles of 100 to 300 mesh before the reduction reaction treatment step. In the reduction reaction treatment step, preferably, the incineration ash temperature is maintained at about 300 ° C. to 600 ° C. (furnace temperature 300 to 900 ° C.) for 20 to 40 minutes, so that the oxides of metals and titanium in the incineration ash The reaction proceeds with. It is preferable to activate and stabilize the activity of the produced catalyst by providing a stabilization treatment step after heat treating the incinerated ash and the oxide of titanium. This stabilization reaction treatment step is preferably carried out by maintaining the treatment temperature at 200 to 450 ° C. for 40 to 60 minutes.

[Incineration ash with activated catalytic capacity and adsorption capacity]
The component composition of this catalyst (incinerated ash with activated catalytic capacity and adsorption capacity) is not clear, but the main component is a poorly soluble material containing titanium composite metal, iron oxide, alumina, calcium, silica, magnesium, etc. It is thought to consist of compounds. When the elution test of the catalyst manufactured by this invention was done, the result of Table 2 was obtained. It was found that there was almost no elution of cadmium, lead, hexavalent chromium, arsenic, mercury and selenium compounds.

  Incinerated ash contains various elements, but compounds are dissociated from the atoms, molecules, and crystals, and are used as recycled resources due to the synergistic effect of catalyst activity and element properties. The product obtained is not only useful as a catalyst for incineration ash low-temperature re-incineration catalyst, dehydration reaction or hydrogenation reaction catalyst, and deodorization catalyst, but also as soil-related materials, fertilizer, hog raising and poultry deodorizing agents as agricultural materials, As civil engineering and building materials, there are a wide range of uses such as ground improvement materials, bricks / blocks, and snow melting materials.

Next, the processing method of incineration ash and the characteristic of a product are demonstrated concretely.
[Example 1]

  Incinerated ash samples in Example 1 were collected from a stoker furnace type incinerator and a fluidized bed furnace type incinerator. The catalyst production apparatus of the present invention has facilities such as a reduction reaction facility, a stabilization reaction facility, and a flue gas treatment facility of an incineration ash recycling plant system.

(1) Receiving / supplying equipment: receiving: raw ash receiving pit 100 m ³ , supplying: ash crane 13 ton / h, receiving hopper 10 m ³ , feeder 15 ton / h
(2) Sorting equipment: Particle size sorting: Vibrating sieve (screen mesh 50 mm, particle size 50 mm or more excluded, particle size 50 mm or less to the next process) Iron sorting: Magnetic separator [Iron exclusion (relatively coarse iron)]
(3) Crushing treatment: Crushing to a particle size of 100 mesh or less (4) Reduction reaction equipment: Atmospheric temperature of about 900 ° C., incineration ash temperature of about 600 ° C., processing time of about 40 minutes, additive (complex oxide of titanium), oxygen concentration About 6%, heating source (A heavy oil)
Main reaction: Dechlorination of organic chlorine compounds; Decomposition of dioxins in ash; Thermal decomposition of organic chlorine compounds; Decomposition of dioxins in furnaces; Reaction of heavy metal compounds and composite oxidation of titanium, imparting catalytic activity (5) Crushing and crushing equipment: crushing equipment: particle size of 10 to 20 mm or less, iron sorting: iron removal (relatively fine iron), crushing treatment: particle size 100 mesh (95%)
(6) Stabilization reaction equipment: Processing temperature of about 200 ° C, processing time of about 60 minutes, oxygen concentration of about 6% Heating source (utilizing waste heat)
When the concentration of dioxins in the produced catalyst was measured, the “toxic equivalent” was “0.000”. Moreover, when the evaluation experiment of the heavy metal elution property of the product was conducted, the elution of heavy metals was hardly recognized.
[Example 2]

  The incinerated ash sample was taken from a stoker furnace type incinerator. The catalyst of the present invention was produced in the same manner as in Example 1. A recycling plant system for producing a catalyst from incineration ashing has a drying treatment facility, a reduction reaction facility, and a stabilization treatment facility, and the drying treatment facility is attached to the facility of Example 1. The amount of oxygen was set to 3% to suppress the reaction by the oxygen medium. In a reducing atmosphere, particularly harmful elements are more likely to react with sulfur than oxygen, and silicates are more likely to react with oxygen than sulfur.

(1) Dioxin decomposition treatment Drying treatment treatment Furnace temperature 800-900 ° C Effect Reduction of moisture content of incinerated ash (2% or less)
Thermal decomposition of dioxins in flue gas Grinding treatment process Treatment Dry incineration ash is pulverized to a particle size of 100 mesh or less Effect of reaction rate improvement and stabilization by increasing surface area of incineration ash (2) Primary reaction treatment process (reduction treatment process) Treatment: Addition Mixing agent (main component: titanium oxide) Oxygen concentration in furnace 3%, flue gas treatment equipment: exhaust gas quenching device + bug filter Effect: Dechlorination and thermal decomposition of dioxins in incineration ash, prevention of heavy metal elution [Example 3]

A catalyst was used to separate the fat from the soy sauce cake. Soy sauce cake contains about 18% fat of soybean and wheat. In order to separate the dried soy sauce cake and fat, 10 g of the above catalyst was added to 50 g of soy sauce cake and kneaded and left for 5 hours. 5 g of fats and oils were confirmed in the container to which the catalyst was added. The separation of the fats and oils in this example is considered to be caused by the addition of hydrogen having high electron accepting properties due to the action of the catalyst to separate the fats and oils.
[Example 4]

20 g of the reduced incineration ash produced in Example 1 was sprayed per 1 m ² of the floor of the pig farm, and the odor from the floor disappeared completely after about 10 minutes.
[Example 5]

Using the reduced incineration ash produced in Example 1, the deodorizing effect of livestock manure odor was tested. After adding 50 g of the reduced incineration ash of the present invention to 1 kg of chicken manure in the poultry farm and stirring and mixing uniformly, the smell of chicken manure after about 10 minutes was measured by five subjects. When the change in olfactory odor before and after deodorization was examined, all five subjects judged that the smell of chicken manure had completely disappeared. As a comparative example, chicken dung was similarly treated with untreated incinerated ash crushed to 150 mesh, and all the subjects judged that the odor was slightly reduced.
[Example 6]

The reduction-treated incinerated ash produced in Example 1 was used to improve soil that was contaminated with sewage generated from household waste and had a bad odor. By adding 50 g of the soil conditioner of the present invention to 1 kg of contaminated soil and stirring sufficiently, the stickiness of the soil was eliminated, and the odor based on the sewage was not felt. These soil improvement effects were maintained for a long time.
[Example 7]

  100 kg of the reduced incineration ash produced in Example 2 was added to 1 kg of soil that was contaminated with heavy metals and difficult to handle due to its high water content, and was sufficiently stirred. Contaminated soil treated with the soil amendment material has improved handling and can be transported from the contaminated site to the treatment plant for soil purification treatment.

  The present invention is a detoxification device for contaminated soil, (1) an apparatus for drying contaminated soil, (2) an apparatus for sorting dry contaminated soil into magnetic material-containing soil and non-magnetic soil, and (3) magnetic material. Equipment for classifying and crushing contained soil, (4) equipment for heat-treating magnetic substance-containing soil in a reducing atmosphere, (5) equipment for mixing non-magnetic soil and magnetic substance-containing soil, (6) reducing atmosphere for mixed soil The present invention relates to a detoxification device for contaminated soil having a device for heat treatment in the inside, and (6) a device for recovering the treated soil as a soil that can be restored, and the present invention has a low equipment cost (initial cost). It is characterized by low maintenance costs (running costs), simple facilities, no need for advanced technology, low carbon dioxide emissions, and construction without using high temperatures. Steel for Cheaper, because since the low risk can be simplified safety equipment compared to high temperature, the system is shorter simple plant production period, maintenance costs has the advantage that only a small number of persons less power cost.

  In addition, the present invention is a detoxification treatment of contaminated soil, a part of the contaminated soil is processed and used as a catalyst for detoxification treatment, heavy metals contained in the soil without using chemicals, organic Contaminants such as chlorine compounds and volatile organic compounds can be decomposed, separated or detoxified into a clean soil. In addition, since the recycled resource plant for treating contaminated soil of the present invention has a simple structure, it can be temporarily installed at the contaminated site, so that it can respond quickly to soil contamination in any region. Possible new decontamination technology for contaminated soil can be provided.

DESCRIPTION OF SYMBOLS 1 Supply crane equipment 2 Receiving hopper 3 Conveying device 4 Vibrating sieve 5 No. 1 Magnetic separator 6 Conveying device 7 Reduction reaction device 8 Conveying equipment 9 Crusher 10 2 Magnetic separator 11 Conveying device 12 Crusher 13 Conveying device 14 Stabilization reaction device 15 Conveying device 16, 17 Raw material, cement tank 18, 19 Conveying device 20, 21 1, no. 2 Fixed amount feeder 22 Mixer 23 Transport device 24 Bagging machine

Claims (8)

Decontamination treatment equipment for contaminated soil, collecting equipment for contaminated soil, drying equipment for drying contaminated soil, magnetic separator for sorting dry contaminated soil into magnetic substance-containing soil and non-magnetic soil, specific gravity from magnetic substance-containing soil Device for removing high metal or coarse particles , ground device for sorted magnetic substance-containing soil, reduction heat treatment device for magnetic material-containing soil, reduction heat treatment device for non-magnetic soil and reduced magnetic material-containing soil A detoxification device for contaminated soil, characterized in that a charging device, a reduced heat treatment device for mixed soil, and a soil recovery device for recovering the treated soil as soil that can be restored are disposed.   The detoxification device for contaminated soil according to claim 1, wherein the heat treatment in the reduction heat treatment device for the magnetic substance-containing soil is performed in a range of 400 to 600 ° C.   The detoxification device for contaminated soil according to claim 1 or 2, wherein the heating temperature in the reduction heating device for mixed soil is in the range of 300 to 600 ° C.   4. The detoxifying device for contaminated soil according to any one of claims 1 to 3, wherein the reducing atmosphere has an oxygen concentration of 6% or less.   The detoxification device for contaminated soil according to any one of claims 1 to 4, wherein the soil containing magnetic material is pulverized to 100 mesh or less by a pulverizer.   The detoxification treatment of contaminated soil according to any one of claims 1 to 5, wherein 2 to 40 parts by weight of magnetic substance-containing soil heat-treated in a reducing atmosphere with respect to 100 parts by weight of non-magnetic soil is introduced into a reduction heat treatment apparatus. apparatus. The detoxification device for contaminated soil according to any one of claims 1 to 6, further comprising a charging device for incineration ash or a mixture of reduced ash-reduced products of the incineration ash to a reduction heat treatment device. The detoxification treatment of contaminated soil according to any one of claims 1 to 7, further comprising a gas circulation path for detoxifying exhaust gas from the reduction heat treatment device for mixed soil and circulating the exhaust gas to a drying device through a sealed circuit. apparatus.